The invention disclosed broadly relates to ubiquitous computing and more particularly relates to improvements in short range wireless technology.
Short Range Wireless Systems
Short range wireless systems have a typical range of one hundred meters or less. They often combine with systems wired to the Internet to provide communication over long distances. The category of short range wireless systems includes wireless personal area networks (PANs) and wireless local area networks (LANs). They have the common feature of operating in unlicensed portions of the radio spectrum, usually either in the 2.4 GHz Industrial, Scientific, and Medical (ISM) band or the 5 GHz Unlicensed-National Information Infrastructure (U-NII) band. Wireless personal area networks use low cost, low power wireless devices that have a typical range of ten meters. The best known example of wireless personal area network technology is the Bluetooth Standard, which operates in the 2.4 GHz ISM band. It provides a peak air link speed of one Mbps and a power consumption low enough for use in personal, portable electronics such as PDAs and mobile phones. Wireless local area networks generally operate at higher peak speeds of between 10 to 100 Mbps and have a longer range, which requires greater power consumption. Wireless local area networks are typically used as wireless links from portable laptop computers to a wired LAN, via an access point (AP). Examples of wireless local area network technology include the IEEE 802.11 Wireless LAN Standard and the HiperLAN Standard, which operates in the 5 GHz U-NII band.
The Bluetooth Short Range Wireless Technology
Bluetooth is a short range radio network, originally intended as a cable replacement. It can be used to create networks of up to eight devices operating together. The Bluetooth Special Interest Group, Specification Of The Bluetooth System, Volumes 1 and 2, Core and Profiles: Version 1.1, Feb. 22, 2001, describes the principles of Bluetooth device operation and communication protocols. The devices operate in the 2.4 GHz radio band reserved for general use by Industrial, Scientific, and Medical (ISM) applications. Bluetooth devices are designed to find other Bluetooth devices within their ten meter radio communications range and to discover what services they offer, using a service discovery protocol (SDP).
The SDP searching function relies on links being established between the requesting Bluetooth device, such as a stationary access point device, and the responding Bluetooth device, such as a mobile user""s device. When the mobile user""s device enters within communicating range of the access point, its Link Controller layer in its transport protocol group handles the exchange of inquiry and paging packets to establish the initial link with the access point device. This process is relatively fast, typically being completed in approximately from one to five seconds. Then the Logical Link Control and Adaptation Protocol (L2CAP) layer in the transport protocol group passes the link status up to the layers in the middleware protocol group. The SDP searching function in the middleware protocol group can then be used to find out about application programs in the responding Bluetooth device that may provide desired services. The SDP searching function can require several seconds to complete, depending on the complexity of the search and the size of the device""s registry.
An example application program service that can be discovered by the SDP searching function is the Wireless Application Environment (WAE) graphical user interface (GUI) function of the Wireless Application Protocol (WAP). WAP-enabled wireless devices can use a microbrowser to display content on a small screen of the device. WAP uses a combination of Internet protocols with other protocols especially modified to work with mobile devices. The Internet protocols are: Point to Point Protocol (PPP), Internet Protocol (IP), and User Datagram Protocol (UDP). The special mobile device protocols are: Wireless Transport Layer Security (WTLS), Wireless Transaction Protocol (WTP), Wireless Session Protocol (WSP), and Wireless Application Environment (WAE). It is the WAE that provides the microbrowser user interface for WAP. In order to establish a connection to send content from the requesting access point device to the WAE microbrowser of the responding user""s device, each of the WAP protocol layers WTLS, WTP, WSP, and WAE must be established, which can require several more seconds to complete and possibly significant user interaction on the way.
It can be seen that if the user""s mobile Bluetooth device has enough speed to travel across the communications area of the Bluetooth access point before completing downloading data from a network server, the contact with the server will be irretrievably lost.
The IEEE 802.11 Wireless LAN Standard
The IEEE 802.11 Wireless LAN Standard defines at least two different physical (PHY) specifications and one common medium access control (MAC) specification. The IEEE 802.11(a) Standard is designed for either the 2.4 GHz ISM band or the 5 GHz U-NII band, and uses orthogonal frequency division multiplexing (OFDM) to deliver up to 54 Mbps data rates. The IEEE 802.11(b) Standard is designed for the 2.4 GHz ISM band and uses direct sequence spread spectrum (DSSS) to deliver up to 11 Mbps data rates. The IEEE 802.11 Wireless LAN Standard describes two major components, the mobile station and the fixed access point (AP). IEEE 802.11 networks can be configured where the mobile stations communicate with a fixed access point. IEEE 802.11 also supports distributed activities similar those of the Bluetooth piconets. The IEEE 802.11 standard provides wireless devices with service inquiry features similar to the Bluetooth inquiry and scanning features.
In order for an IEEE 802.11 mobile station to communicate with other stations in a network, it must first find the stations. The process of finding another station is by inquiring. Active inquiry requires the inquiring station to transmit queries and invoke responses from other wireless stations in a network. In an active inquiry, the mobile station will transmit a probe request frame. If there is a network on the same channel that matches the service set identity (SSID) in the probe request frame, a station in that network will respond by sending a probe response frame to the inquiring station. The probe response includes the information necessary for the inquiring station to access a description of the network. The inquiring station will also process any other received probe response and Beacon frames. Once the inquiring station has processed any responses, or has decided there will be no responses, it may change to another channel and repeat the process. At the conclusion of the inquiry, the station has accumulated information about the networks in its vicinity. Once a station has performed an inquiry that results in one or more network descriptions, the station may choose to join one of the networks. The IEEE 802.11 Wireless LAN Standard is published in three parts as IEEE 802.11-1999; IEEE 802.11a-1999; and IEEE 802.11b-1999, which are available from the IEEE, Inc. web site http://grouper.ieee.org/groups/802/11.
In the case of IEEE 802.11 mobile stations, if the user""s mobile device has enough speed to travel across the communications area of the IEEE 802.11 access point before completing downloading data from a network server, the contact with the server will be irretrievably lost.
High Performance Radio Local Area Network (Hiperlan)
The HiperLAN standard provides a wireless LAN with a high data rate of up to 54 Mbps and a medium-range of 50 meters. HiperLAN wireless LANs provide multimedia distribution with video QoS, reserved spectrum, and good in-building propagation. There are two HiperLAN standards. HiperLAN Type 1 is a dynamic, priority driven channel access protocol similar to wireless Ethernet. HiperLAN Type 2 is reserved channel access protocol similar to a wireless version of ATM. Both HiperLAN Type 1 and HiperLAN Type 2 use dedicated spectrum at 5 GHz. HiperLAN Type 1 uses an advanced channel equalizer to deal with intersymbol interference and signal multipath. HiperLAN Type 2 avoids these interference problems by using OFDM and a frequency transform function. The HiperLAN Type 2 specification offers options for bit rates of 6, 16, 36, and 54 Mbps. The physical layer adopts an OFDM multiple carrier scheme using 48 carrier frequencies per OFDM symbol. Each carrier may then be modulated using BPSK, QPSK, 16-QAM, or 64-QAM to provide different data rates. The modulation schemes chosen for the higher bit rates achieve throughput in the range 30-50 Mbps.
The HiperLAN Type 1 is a dynamic, priority driven channel access protocol that can form networks of wireless devices. HiperLAN Type 1 networks support distributed activities similar those of the Bluetooth piconets and IEEE 802.11 independent basic service sets (IBSS). The HiperLAN Type 1 standard provides wireless devices with service inquiry features similar to those of the Bluetooth inquiry and scanning features and the IEEE 802.11 probe request and response features. An overview of the HiperLAN Type 1 principles of operation is provided in the publication HiperLAN Type 1 Standard, ETSI ETS 300 652, WA2 December 1997.
HiperLAN Type 2 is a reserved channel access protocol that forms networks. HiperLAN Type 2 networks support distributed activities similar those of the HiperLAN Type 1 networks, Bluetooth piconets and IEEE 802.11 independent basic service sets (IBSS). HiperLAN Type 2 provides high speed radio communication with typical data rates from 6 MHz to 54 Mbps. It connects portable devices with broadband networks that are based on IP, ATM and other technologies. Centralized mode is used to operate HiperLAN Type 2 as an access network via a fixed access point. A central controller (CC) in the fixed access point provides QoS coordinates the access of the mobile stations support. User mobility is supported within the local service area and wide area roaming mobility can also be supported. An overview of the HiperLAN Type 2 principles of operation is provided in the Broadband Radio Access Networks (BRAN), HiperLAN Type 2; System Overview, ETSI TR 101 683 VI.I.1 (2000-02) and a more detailed specification of its ad hoc network architecture is described in HiperLAN Type 2, Data Link Control (DLC) Layer; Part 4. Extension for Home Environment, ETSI TS 101 761-4 V1.2.1 (2000-12).
In the case of HiperLAN mobile stations, if the user""s mobile device has enough speed to travel across the communications area of the HiperLAN access point before completing downloading data from a network server, the contact with the server will be irretrievably lost.
What is needed is a way of enabling a mobile wireless device to resume an Internet contact with a web site, which was being conducted through a short range wireless access point, but which has been interrupted by moving the mobile device out of the coverage area of the access point.
The invention solves the problem of enabling a mobile wireless device to resume an Internet contact with a web site, which was being conducted through a short range wireless access point, but which has been interrupted by moving the mobile device out of the coverage area of the access point. Short range wireless systems include wireless personal area networks (PANs), such as Bluetooth networks and IrDA Infrared Data Protocol networks, and wireless local area networks (LANs), such as the IEEE 802.11 wireless LANs and HiperLAN networks. The invention involves the use of mobile wireless devices that are equipped with both short range wireless communications circuits and with cellular telephone communications circuits. An example of such a mobile wireless device is a Bluetooth-equipped cellular telephone.
During the period when a mobile wireless device is within the coverage area of a short range wireless access point, it sends a request for service to be obtained over the Internet from a network server. The short range wireless access point forwards that request over the Internet to the server, augmented with additional information including the network address and geographic location of the access point. The short range wireless access point receives a response message over the Internet from the server, including a global/local parameter. The global/local parameter will notify the mobile wireless device whether the requested service is available outside the coverage area of the short range wireless access point. The access point forwards the response message to the mobile wireless device, which uses the information in the message to contact the server over the Internet to download web pages or to conduct other server operations.
Regions outside the coverage area of the short range wireless access point are covered by regional cellular telephone access points, such as cellular telephone base stations. Suitable cellular telephone systems include GSM, GPRS, UMTS, EDGE, and the like. In accordance with the invention, if the mobile wireless device detects that it has left the coverage area of the short range wireless access point while in contact with the server, it will determine whether the global/local parameter indicates that the service is global. For example, the server may have been in the process of downloading web pages. If the parameter is global, then the mobile wireless device stores a bookmark of the server""s URL, for example the URL and path name for one of the prior web pages downloaded from the server. The mobile wireless device displays a notice to the user offering the user the option of continuing the contact with the server over the regional cellular telephone network.
If the user selects to continue the contact with the server, then a stored handover address is accessed. The handover address may be stored in the mobile wireless device or alternately, it may be stored in the short range wireless access point. The stored handover address may be a default address or alternately, it may be a handover address included in the prior response message from the server. The handover address will typically be the telephone number of a protocol gateway, such as a WAP gateway, connected between the cellular telephone network and the Internet. A cellular telephone connection is made by the mobile wireless device with the regional cellular telephone access point. Then, a cellular telephone call is placed to the protocol gateway. When the call is completed over the telephone network from the mobile wireless device to the protocol gateway, the mobile wireless device sends a message to the protocol gateway.
For example, if the mobile wireless device includes the Wireless Application Protocol (WAP) and if the protocol gateway is a WAP gateway, then a Wireless Session Protocol (WSP) request can be generated in the mobile wireless device. The WSP request is generated by a Wireless Markup Language (WML) xe2x80x9c less than go greater than xe2x80x9d element in the application program of the mobile wireless device, which specifies the server URL. The message can include an HTTP request method, either the GET or the POST method. When GET is used, the data being sent to the server is appended to the end of the URL. When POST is used, the data is passed in the body of the message. The WAP gateway then converts the WSP request into an HTTP request and forwards it over the Internet to the network server.
Depending on the request, the server responds by resuming the operations it had previously been conducting in its prior contact with the mobile wireless device. For example, WML, HTML, or graphics files can be returned by the server to the WAP gateway. For example, the server can respond to a GET method request by sending the requested web page to the protocol gateway. Alternately, the server can respond by executing CGI, ASP, or JSP scripts or other server programs to dynamically generate WML or HTML content to be returned to the WAP gateway. The protocol gateway then performs an HTML to WML conversion of the content, followed by WML encoding to form the WSP response message. The WSP response message is then transmitted by the WAP gateway over the telephone network to the cellular telephone access device. The cellular telephone access device then transmits the WSP response message containing the content, over the cellular telephone air link to the mobile wireless device.
Additional options can be offered to the user when resuming the service. Alternately, the user may choose to save the URL link in the terminal memory and continue the service later via digital video broadcast or other broadcasting medium.
In this manner, the mobile wireless device can resume an Internet contact with a web site, which was being conducted through a short range wireless access point, but which has been interrupted by moving the mobile device out of the coverage area of the short range wireless access point.